1. Field of the Invention
An abrasive cleaning apparatus including an adjustable nozzle support means having a horizontal positioning means to permit movement of a plurality of nozzles in a plane parallel to a work surface and a vertical and angular adjustment means to adjust the vertical position and angle of the plurality of nozzles relative to the work surface.
2. Description of the Prior Art
Sand blasting of surfaces cleaned preparatory to painting and simply cleaning in the case of stone or brick walls is a common practice. Generally, this is accomplished by an operator positioned on a scaffold or other suitable support manually manipulates at least one discharge nozzle. Obviously, the presence of the operator in the work zone makes this an extremely dirty and hazardous occupation. Moreover, the limited volume of sand blasted against the surface by a single nozzle is very inefficient.
As a result, abrasive blast apparatus, particularly used for large surface areas, may employ multiple rather than a single blast nozzle. The obvious advantage of this being a greatly increased blast pattern. Due to the increased weight and speed of operation, those nozzles are often mounted on movable carriages or platforms on which the operator rides. The platform is movable laterally and vertically along the area to be cleaned and results in significant labor saving devices.
Unfortunately, a number of difficulties have been experienced which hindered general acceptance and wide use for the multi-nozzle head. For example, many multi-nozzle heads are of a type in which the sand and air are delivered and mixed in a common reservoir from which jet streams are propelled simultaneously from the nozzles all of which communicate directly with the reservoir. In another configuration, the operator may be provided with two separate nozzles each having its own supply lines. In either of these arrangements, individual control of the nozzles is lacking to the extent that the blast stream in one nozzle cannot be cut off independently of the other. Such independent manipulations of the blast from the different nozzles is desirable in situations involving spots or areas which present difficult cleaning problems. The blast from one nozzle must work on this different area for a prolonged period, during which time and other blasts will be cutting away injuriously at the clean metal or surrounding areas.
Another difficulty with previous multi-blast carriage arrangements is that the units are very cumbersome and complex so as to be suitable only for special cleaning operations. Also many such multiple nozzle machines have lacked adequate flexibility of movement and could not be easily manipulated.
More unique problems exist with respect to the development of such apparatus for cleaning the undersides of ships in dry dock where there is very little clearance between the hull and the floor of the dry dock. Bulky machines cannot reach into that area. After such an apparatus is placed under the hull, it must be constructed so as to position a plurality of nozzles so as to efficiently clean the under surfaces of the ship.
Thus, there is a clear need for an efficient, flexible and easily moved multiple nozzle blasting apparatus for cleaning the undersides of ships in dry docks.